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First implementation for 'const' variables

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A variable can be declared const, which means it cannot be assigned to,
with the syntax 'local <const> name = exp'.
This commit is contained in:
Roberto Ierusalimschy
2019-05-17 11:11:44 -03:00
parent 347d6961ac
commit d9f40e3f6f
7 changed files with 207 additions and 58 deletions
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36
lcode.c
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@@ -678,11 +678,12 @@ void luaK_setoneret (FuncState *fs, expdesc *e) {
void luaK_dischargevars (FuncState *fs, expdesc *e) {
switch (e->k) {
case VLOCAL: { /* already in a register */
e->u.info = e->u.var.idx;
e->k = VNONRELOC; /* becomes a non-relocatable value */
break;
}
case VUPVAL: { /* move value to some (pending) register */
e->u.info = luaK_codeABC(fs, OP_GETUPVAL, 0, e->u.info, 0);
e->u.info = luaK_codeABC(fs, OP_GETUPVAL, 0, e->u.var.idx, 0);
e->k = VRELOC;
break;
}
@@ -938,12 +939,12 @@ void luaK_storevar (FuncState *fs, expdesc *var, expdesc *ex) {
switch (var->k) {
case VLOCAL: {
freeexp(fs, ex);
exp2reg(fs, ex, var->u.info); /* compute 'ex' into proper place */
exp2reg(fs, ex, var->u.var.idx); /* compute 'ex' into proper place */
return;
}
case VUPVAL: {
int e = luaK_exp2anyreg(fs, ex);
luaK_codeABC(fs, OP_SETUPVAL, e, var->u.info, 0);
luaK_codeABC(fs, OP_SETUPVAL, e, var->u.var.idx, 0);
break;
}
case VINDEXUP: {
@@ -1165,25 +1166,30 @@ static int isSCnumber (expdesc *e, lua_Integer *i, int *isfloat) {
** values in registers.
*/
void luaK_indexed (FuncState *fs, expdesc *t, expdesc *k) {
lua_assert(!hasjumps(t) && (vkisinreg(t->k) || t->k == VUPVAL));
lua_assert(!hasjumps(t) &&
(t->k == VLOCAL || t->k == VNONRELOC || t->k == VUPVAL));
if (t->k == VUPVAL && !isKstr(fs, k)) /* upvalue indexed by non string? */
luaK_exp2anyreg(fs, t); /* put it in a register */
t->u.ind.t = t->u.info; /* register or upvalue index */
if (t->k == VUPVAL) {
t->u.ind.t = t->u.var.idx; /* upvalue index */
t->u.ind.idx = k->u.info; /* literal string */
t->k = VINDEXUP;
}
else if (isKstr(fs, k)) {
t->u.ind.idx = k->u.info; /* literal string */
t->k = VINDEXSTR;
}
else if (isCint(k)) {
t->u.ind.idx = cast_int(k->u.ival); /* integer constant in proper range */
t->k = VINDEXI;
}
else {
t->u.ind.idx = luaK_exp2anyreg(fs, k); /* register */
t->k = VINDEXED;
/* register index of the table */
t->u.ind.t = (t->k == VLOCAL) ? t->u.var.idx: t->u.info;
if (isKstr(fs, k)) {
t->u.ind.idx = k->u.info; /* literal string */
t->k = VINDEXSTR;
}
else if (isCint(k)) {
t->u.ind.idx = cast_int(k->u.ival); /* int. constant in proper range */
t->k = VINDEXI;
}
else {
t->u.ind.idx = luaK_exp2anyreg(fs, k); /* register */
t->k = VINDEXED;
}
}
}